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Hydrocarbons · Question 11

JEE Main 2026 (Online) 28th January Morning ShiftMCQMedium📈 Topic in 32% papers+4−1
1

Ph-CH=CH2 [HBr](PhCOO)2 Product Consider the above reaction Identify the correct statements. Choose the correct answer from the options given below :

  1. A & E Only
  2. A, B & D Only
  3. A, C & E Only
  4. C, D & E Only

Answer

(3) A, C & E Only

Solution

In the presence of benzoyl peroxide, HBr adds to styrene by a free radical mechanism (peroxide effect):

Initiation: (C6H5COO)2 2C6H5COO 2C6H5 + 2CO2

C6H5 + HBr C6H6 + Br benzene is formed as a byproduct (C correct) and the peroxide generates Br , not H (B incorrect).

Propagation: Br adds to the terminal carbon so that the more stable benzylic radical is formed (A correct):

C6H5-CH=CH2 + Br C6H5- CH-CH2Br

C6H5- CH-CH2Br + HBr C6H5-CH2-CH2Br + Br

1-Bromo-2-phenylethane is the major (anti-Markovnikov) product, not the minor one (D incorrect).

Without peroxide, HBr adds by electrophilic addition through the more stable benzylic carbocation C6H5- CH-CH3, giving 1-bromo-1-phenylethane (E correct).

A, C and E are correct.

Answer: (3)

JEE Main 2026 (Online) 28th January Morning Shift

Keep practising — Hydrocarbons

2

The reactions which produce alcohol as the product are : Choose the correct answer from the options given below :

  1. B, D and E Only
  2. A and D Only
  3. A, C and E Only
  4. C and D Only
JEE Main 2026 (Online) 28th January Evening Shift
3

Consider the following compounds : [figure] Arrange these compounds in the increasing order of reactivity with nitrating mixture.

  1. c < b < a
  2. b < c < a
  3. c < a < b
  4. b < a < c
JEE Main 2026 (Online) 23rd January Morning Shift
4

But-2-yne and hydrogen (one mole each) are separately treated with (i) Pd/C and (ii) Na/ liq. NH3 to give the products X and Y respectively. [figure] Identify the incorrect statements. Choose the correct answer from the options given below :

  1. B and D Only
  2. A and C Only
  3. A and B Only
  4. B and C Only
JEE Main 2026 (Online) 23rd January Morning Shift
5

[figure] Identify (P)

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 23rd January Evening Shift
6

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below

  1. Statement I is incorrect but Statement II is correct
  2. Both Statement I and Statement II are correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is correct but Statement II is incorrect
JEE Main 2026 (Online) 22nd January Morning Shift
7

The cycloalkene (X) on bromination consumes one mole of bromine per mole of (X) and gives the product (Y) in which C : Br ratio is 3:1. The percentage of bromine in the product (Y) is %. (Nearest integer) (Given : molar mass in g mol-1 H : 1, C : 12, O : 16, Br : 80)

JEE Main 2026 (Online) 22nd January Morning Shift
8

Consider the following reaction : [figure] The product Y formed is :

  1. 2-methylhex-3-yne
  2. 5-methylhex-2-yne
  3. Isopropylbut-1-yne
  4. 2-methylhex-2-yne
JEE Main 2026 (Online) 22nd January Evening Shift
9

The dibromo compound [P] (molecular formula: C9H10Br2) when heated with excess sodamide followed by treatment with dilute HCl gives [Q]. On warming [Q] with mercuric sulphate and dilute sulphuric acid yields [R] which gives positive Iodoform test but negative Tollens' test. The compound [P] is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 22nd January Evening Shift
10

Identify A in the following reaction. [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 21st January Morning Shift
11

[figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 8th April Evening Shift

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